This invention relates to fuel cells and, in particular, to fuel cells in which the fuel process gas for the fuel cells is derived by reforming of the fuel supply internal of the fuel cells.
A variety of fuel cell arrangements have been proposed in which the fuel process gas for the cells is internally generated. In U.S. Pat. No. 3,488,226 internal reforming is carried out by situating the reforming catalyst directly in the anode chamber of the fuel cells. U.S. Pat. No. 4,182,795, on the other hand, utilizes a fuel cell chamber for the reforming catalyst which is isolated from the cell electrolyte.
The above fuel cell arrangements utilizing internal reforming are attractive because they eliminate the need for an external fuel processor and because they provide increased system efficiency. Also, there is a good match between the heat flows as the fuel cell electrochemical reaction is exothermic while the in situ fuel reforming reaction is exothermic.
The presence of the reforming catalyst in the fuel cell, however, tends to make the temperature distribution or profile of the cell in the direction of the fuel gas flow non-uniform, since the reforming reaction cools the cell to a greater degree in the regions thereof adjacent the point of introduction of the fuel supply. U.S. Pat. application No. 642,375, assigned to the same assignee hereof, discloses one technique for counteracting this effect by non-uniformly distributing reforming catalyst over the reforming chamber. Researchers, however, are still looking for less complex and simpler arrangements for negating the non-uniform cooling effect of the reforming catalyst.
It is therefore an object of the present invention to provide a fuel cell apparatus which utilizes internal reforming but which tends to avoid the non-uniformity in temperature profile which normally accompanies the reforming reaction.